How Umpire Evaluation Works
Approximately 60 umpires serve in NPB, assigned to the Central and Pacific Leagues. The NPB Umpiring Department conducts year-round evaluations across four categories: strike-ball accuracy, out-safe accuracy, game management (pace, conflict resolution), and rules knowledge. Tracking system introduction in the 2020s enabled objective quantification of strike zone accuracy. MLB introduced Zone Evaluation in 2008, with NPB following approximately 15 years later. Average umpire accuracy is approximately 90-92%, but drops to 70-75% on borderline pitches.
Technology Transforming Umpiring
Tracking technology is fundamentally changing umpiring. NPB began testing Automated Ball-Strike (ABS) systems in farm games from 2022. ABS uses cameras and sensors to track pitch trajectories and automatically determine strike zone passage. MLB deployed ABS in select minor league games in 2024, with umpires receiving calls via earpiece in a challenge system. NPB discusses first-team ABS adoption, but reconciling with the traditional view that human judgment is part of baseball remains challenging. Former Hanshin manager Akifu Okada stated that machine-judged calls would remove baseball's flavor, representing the cautious faction's prominent voice.
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Umpire Career Paths
Becoming an NPB umpire requires attending the Professional Baseball Umpire School (held each December) and passing entrance exams with approximately 10% acceptance rate. New umpires spend 3-5 years in the farm system before first-team promotion. First-team umpire annual salaries range from 10-15 million yen for veterans. Compared to MLB umpires averaging approximately $400,000 (about 60 million yen), NPB umpire compensation falls significantly short. The pinnacle is serving as home plate umpire for the Japan Series or All-Star Game - the highest honor in umpiring. Mandatory retirement is at 57, with 30-plus year careers not uncommon.
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Challenges and Reform
NPB's umpiring system faces several challenges. The primary issue is insufficient accountability for incorrect calls. MLB expanded replay review in 2014, allowing managers to challenge and overturn calls. NPB introduced replay review in 2010 but with limited scope - ball-strike calls remain unreviewable. Former SoftBank manager Sadaharu Oh stated that umpires are human and make mistakes, emphasizing the importance of systems to acknowledge and correct errors. Improving umpire accuracy, phased ABS introduction, and better umpire compensation are essential initiatives for elevating NPB game quality.